Tulathromycin A
[CAS# 217500-96-4]

Identification

• Classification: API >> Antibiotics >> Other antibiotics
• Name: Tulathromycin A
• Synonyms: (2R,3S,4R,5R,8R,10R,11R,12S,13S,14R)-13-[[2,6-Dideoxy-3-C-methyl-3-O-methyl-4-C-[(propylamino)methyl]-a-L-ribo-hexopyranosyl]oxy]-2-ethyl-3,4,10-trihydroxy-3,5,8,10,12,14-hexamethyl-11-[[3,4,6-trideoxy-3-(dimethylamino)-b-D-xylo-hexopyranosyl]oxy]-1-oxa-6-azacyclopentadecan-15-one
• Molecular Formula: C₄₁H₇₉N₃O₁₂
• Molecular Weight: 806.08
• CAS Registry Number: 217500-96-4
• EC Number: 638-829-0
• SMILES: CCCNC[C@@]1([C@@H](O[C@H](C[C@@]1(C)OC)O[C@H]2[C@@H]([C@H]([C@](C[C@H](CN[C@@H]([C@H]([C@]([C@H](OC(=O)[C@@H]2C)CC)(C)O)O)C)C)(C)O)O[C@H]3[C@@H]([C@H](C[C@H](O3)C)N(C)C)O)C)C)O

Properties

• Solubility: <8 mg/mL (DMSO) (Expl.)
• Density: 1.17±0.1 g/cm³, Calc.^*
• Index of Refraction: 1.536, Calc.^*
• Boiling Point: 853.8±65.0 ºC (760 mmHg), Calc.^*
• Flash Point: 470.2±34.3 ºC, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H317-H319-H412
• Precautionary Statements: P261-P264-P273-P280-P302+P352-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin sensitization	Skin Sens.	1	H317
Eye irritation	Eye Irrit.	2	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Reproductive toxicity	Repr.	2	H361
Acute toxicity	Acute Tox.	4	H302

Discovory and Applicatios

Tulathromycin A is a macrolide antibiotic used primarily in veterinary medicine to treat respiratory infections in livestock. It was developed to address bacterial infections in cattle and swine, particularly those caused by pathogens associated with bovine respiratory disease (BRD), swine respiratory disease (SRD), and infectious bovine keratoconjunctivitis. Tulathromycin A belongs to the triamilide subclass of macrolides, which are characterized by their 15-membered lactone ring structure, providing a broad spectrum of antibacterial activity against gram-positive and gram-negative bacteria.

The discovery of tulathromycin A was driven by the need for a long-acting antibiotic with high tissue penetration and efficacy against respiratory pathogens. Researchers focused on modifying existing macrolide structures to enhance pharmacokinetics and improve efficacy in veterinary applications. Tulathromycin A was developed through semi-synthetic modifications, resulting in improved bioavailability, increased stability, and prolonged therapeutic effects compared to earlier macrolides such as erythromycin and tilmicosin.

Tulathromycin A is widely used to treat respiratory diseases caused by *Mannheimia haemolytica*, *Pasteurella multocida*, and *Histophilus somni* in cattle, as well as *Actinobacillus pleuropneumoniae* and *Mycoplasma hyopneumoniae* in swine. The antibiotic's unique pharmacokinetic properties allow for a single-dose administration that maintains effective plasma and tissue concentrations for an extended period, reducing the need for repeated dosing and minimizing stress in livestock.

The mechanism of action of tulathromycin A involves binding to the bacterial 50S ribosomal subunit, inhibiting protein synthesis and preventing bacterial growth. This mode of action is particularly effective against respiratory pathogens, which often reside in intracellular environments. The prolonged half-life of the drug allows it to accumulate in lung tissues, making it highly effective for treating respiratory infections.

Tulathromycin A is also valued for its role in reducing antimicrobial resistance in veterinary medicine. Because it requires fewer doses than traditional antibiotics, it helps limit the overuse of antimicrobials in livestock, which is a significant concern in global efforts to combat antibiotic resistance. However, regulatory agencies emphasize the importance of responsible use to prevent cross-resistance with human macrolide antibiotics.

Beyond livestock applications, tulathromycin A continues to be studied for potential uses in treating infections in other animals, including poultry and companion animals. Research is ongoing to optimize dosing strategies, explore synergistic effects with other antimicrobial agents, and evaluate its effectiveness against emerging bacterial threats in veterinary medicine.